A Study in Four
by hmmga
Summary: A friendship that shakes Hogwarts to its core. A Slytherin and a Hufflepuff. A Holmes and a Watson. Add some mysterious disappearances, and you've got yourself a young detective, and a friend who tries to steer him towards some semblance of normality...
1. Chapter 1

**Hello all,**

**This is a Sherlock and Harry Potter crossover, and therefore anything you recognise belongs to JK Rowling, Arthur Conan-Doyle, or the BBC. However, while have taken the concepts for the characters, I have also tried to add my own twist to them, so they may not be the traditional perceptions that people are used to. My Sherlock and John are still growing up, making friends, discovering their talents, and finding their places in the world. This is the first instalment of what will hopefully become a series, and I decided to start right at the beginning: first year. Some avid Sherlockians will notice some rather big deviations from the originals. For instance, Mycroft is only five years older than Sherlock, and Harry Watson is younger than John. I have also not completely followed the plot-lines of the originals, for what I hope are obvious reasons. This story is **_**very**_** loosely based on A Study in Scarlet. **

**It is set five years after the war, and while a lot of characters from the original series do appear at some point, they are not the main focus of the plot.**

**Feel free to comment and I will be happy to answer any questions. The story is now on the last chapter in notebook form, so I hope I will be able to update regularly!**

**Chapter 1**

It was the first of September, and the first years were gathered in a frightened huddle by the staff table, highly aware of the eyes of the school that were scrutinising them. Amongst them was a John Hamish Watson, who couldn't help feeling a bit overwhelmed. It had been a very strange day, and he had already realised that the magical world was very different to the 'muggle' surroundings he was used to. He took a deep breath in as the hat finished singing, and felt the comforting weight of his father's pendant against his chest. He hadn't taken it off since his death. A tiny little wizard clambered onto a chair, and pulled out a sheaf of parchment longer than he was. He began reading out names.

"Allen, Joelle!"

The girl sat on the stool, and pulled the hat onto her head.

"GRYFFINDOR!"

'Anderson, Fred', and 'Brown, Elizabeth' went to Gryffindor too, but 'Camu, Rose' became the first Slytherin, and the green and silver table exploded with cheers. John breathed deeply again, and tried not to panic. Mary Morston, a girl from the train had attempted to explain the house system to him, but he had to admit that he hadn't fully grasped it. He turned his attention back to the names.

"Grant, Thomas!"

"GRYFFINDOR!"

"Gribble, Fabio!"

"SLYTHERIN!"

"Holmes, Sherlock!"

This time he recognised the face. The boy on the stool had sat for a while in their compartment, muttering about 'Mycroft's _personal _opinions. He was an odd looking boy, pale and thin, and he had not spoken directly to either him or Mary at all. There was a very long wait; the hat seemed to be facing a hard decision. The boy's green eyes were flickering across the hall, surveying the students.

"SLYTHERIN!" screamed the hat. The green and silver table cheered again, but the boy threw a triumphant glance at the Ravenclaw table before taking his seat. The sorting continued without a hitch. When 'Morston, Mary' was called, John gave her an encouraging smile, which she returned as her blonde hair vanished under the hat.

"HUFFLEPUFF!" it called immediately.

The names continued to come, and soon there were only a few people left.

"Watson, John!"

John sat on the stool with trembling legs.

_Hmm, tricky. Nerves of steel, but not reckless enough for Gryffindor. Ooh, another one. Well, isn't that interesting…_

"HUFFLEPUFF!"

John scurried gratefully to sit next to Mary, who gave him a friendly smile. Very soon the sorting was over, and headmistress McGonagall got to her feet.

"Welcome!" she smiled. "There are a few start of term notices, but for now, let the feast begin!"

Food materialised on the plates before them. John had never seen so much food in one place, and certainly not recently. He piled his plate, listening to his fellow first year's conversations.

"Well I'm a pureblood," Mary was saying. "But my whole family has been in Hufflepuff."

"Lucky you," said Peter miserably. "My parents were both in Slytherin, dunno what they'll do to me now."

"I didn't even know about magic until I got my letter," said Jenny.

"Same," chanted the twins, Edward and Emily. "We were very surprised."

"Me too," said John, joining in for the first time. "I thought mum was gonna faint."

The others laughed, and the chatter continued until the food vanished off the plates, and Professor McGonagall stood up once more.

"Now, just a few notices… will the first years please note that the forbidden forest is strictly out of bounds for all students. I would also like to announce some staff changes for the coming year. As you may know, Madame Pomfrey has decided to retire, and I would like to present the new school nurse, Mrs Hudson."

There was scattered applause.

"Also, our old caretaker Argus Filch has also decided to leave us, and so could you please give a warm welcome to Mr Carson."

There was more clapping, but this seemed a little more enthusiastic.

"Lessons begin tomorrow morning. Dismissed!"

As one, the school rose to their feet, and began chattering excitedly. A tall boy with a yellow prefect's badge on his robes darted down to the first years.

"First-years! Hufflepuff first-years! Everyone here? Good! Follow me!"

As they left the hall, John caught a glimpse of the skinny boy who had taken so long to sort. He was being badgered by a slightly pudgy boy with a Ravenclaw prefect's badge. He seemed rather cross about something. Around them, people were snickering.

XXX

Sherlock glanced around curiously as he entered the Slytherin common room. Older students brushed against him, and he memorised the scents instinctively, as his eyes picked up the tiniest details…

"Okay, listen up!" the prefect called. "This is the Slytherin common room."

_Obviously._

"The girl's dormitories are down that corridor, and the boys are the corridor opposite. Boy boys, _don't _try and get into the girl's dorms, if you do you're in for a nasty surprise! Now if you need anything you can come to me, or my lovely girlfriend here…" he indicated a girl standing quite close to Sherlock. She waved back at him in a sickly fashion. By the time the prefect blew a kiss back, Sherlock had had enough.

"She's sleeping with the Quidditch captain," he announced to the room. The whole house went deathly quiet. Without another word, Sherlock stalked out to find his dormitory. It was the first door he reached, and labelled 'first-years'. His trunk was already next to a bed, and he rummaged inside for pyjamas. After a while, the door creaked open, and the other four boys flooded in.

"A huge fight's broken out in the common room," Flint informed him in amazement. "How did you know?"

"She was wearing his deodorant," he sighed. "It was a simple deduction."

He climbed onto the four poster bed and drew the curtains shut, sincerely hoping that they wouldn't expect him to make conversation every night.


	2. Chapter 2

**Here is the next chapter. Apologies to the person who thought that the last chapter was 'a little flat', but I have never written a mystery before, and I always find I don't particularly like stories where the first chapter is crammed with info. This chapter is about 'the first day' (sorry it has to be done), but it also has a little more background, though mostly of John. Sherlock is, and always will be, quite a mysterious character.**

**This story will mostly be from John's perspective, mostly because Sherlock's thoughts are so difficult to write whilst trying to keep the cold inhuman mentality he's supposed to have. If anybody feels that Sherlock is ever acting a bit out of character, please bear in mind that he is a first year, and I am not Arthur Conana-Doyle, Stephen Moffat, Mark Gatis, or even Benedict Cumberbatch, (though I wish I was).**

**Oh, and I'm not JK Rowling either, just in case any of you weren't sure.**

**Chapter 2**

The noise in the breakfast hall was tumultuous as John and his friends entered. Everybody was still catching up with their friends, and telling stories of their summer holidays. John scuttled next to Mary and Peter, and began helping himself to toast.

"So what have we got first?"

"Transfiguration," said Peter, checking his timetable. "Then charms with the Gryffindors, and potions with the Slytherin… that's funny, I was told that Gryffindor and Slytherin were always together for potions."

"They did," said Mary. "But after the war they managed to blow up a classroom, so Slughorn put his foot down."

"The war?"

"We still have a lot of classes with the other houses though, so…"

"Sorry- what war?"

Everyone in the immediate vicinity turned to stare, but John wasn't the only one looking confused.

"A few years ago," said Mary, "about five years ago now, there was a big war against an evil wizard. He had gathered some followers, and taken control of the wizarding world. No-body could stop him, but then there was a huge battle right here in the school. The wizard was eventually killed by a boy named Harry Potter, but a lot of people died that day. After that, there was a lot of bitterness between the houses, even the ones who used to get along, so the teachers had to do a lot of juggling with the classes."

"I- I see."

"It's a lot to take in," she smiled apologetically. "I'm sorry."

"No, that's ok, I have a lot to learn."

"My mother's a muggleborn, she said it was a bit overwhelming."

"Tell me about it."

The bell rang for first lesson, and people began filing out. John and Mary found a hand on their shoulder. It was the prefect from the night before.

"I'm to take you to your first class."

OOO

The transfiguration teacher was a jolly looking man who rapidly became sterner and stricter as the class progressed. He told them at the very beginning that there was to be no messing around in his classes.

"Transfiguration is one of the hardest and most dangerous subjects you will study at this school. It is imperative that you give it your upmost attention."

After copying some notes, everyone was handed a match, and told to turn it into a needle. Quite a few of John's classmates looked positively alarmed at being asked to do magic so quickly. By the end of the class, no-one had managed to make any difference to their matches. However, Professor Macmillan seemed unperturbed, and waved them off with a smile and directions to the charms classroom.

The Gryffindors were already there when they arrived, sat together in a red and gold block on the left side of the room. The Hufflepuffs took their seats on the right. The lesson consisted entirely of note-taking. It was only as they left the lesson that John realised that while there hadn't seemed to be much animosity between the Gryffindors and Hufflepuffs, there hadn't been any interaction.

XXX

Sherlock was bored. His only class so far had been Herbology, and _that_ was mind-numbingly simple. While he could respect Professor Sprout's intentions to have them 'dive straight in', re-potting flowers was something a six year old could do. He'd handled the more dangerous plants in his mother's greenhouses, and probably knew as much about botany as the Professor herself. He sighed, and edged further down the Slytherin table. People were stupid, but at last they were learning to leave him alone. Some people were even starting to shun him deliberately. That was fine by him.

Leaving his lunch uneaten he left for potions as early as possible. He was the first to arrive, so settled himself at a table at the very back of the classroom. It was in the corner, and he felt safer there, more secure there, safer. Resigning himself to at least ten minutes in the empty classroom, he pulled out a book on advanced transfiguration that he'd 'borrowed' from his brother's collection. Soon he was completely absorbed in the book, his brain drinking in any relevant data.

The Hufflepuffs were the first to arrive, and their chatter disturbed Sherlock. He glanced up, irritated even though they were on the other side of the classroom. The Slytherin joined them soon after, sitting as far away as possible from the members of the other house. The classroom was full, but no-one had taken the seat next to Sherlock, for which he was grateful. At that moment, Professor Slughorn waddled into the room, beaming at the students.

"Hello!" he smiled brightly. "Welcome to your first potions lesson! I am Professor Slughorn…"

_Obviously_, thought Sherlock, examining the teacher critically. But before he could make any deductions the dungeon door burst open again, and a red-faced boy hurried in.

"Ah, glad you could join us Mr…"

"Watson, I'm so sorry sir, I got lost."

"That's quite alright m'boy; just sit down over there next to that young gentleman."

Sherlock curled his fingers into fists as the boy took the only available seat in the room. It seemed that he'd have to put up with a table mate after all.

"Right, now that you are seated, these will be your places for the entire year."

Sherlock scowled. He was stuck with the Hufflepuff.

"Potions is _the_ most dangerous and difficult art you will learn in this school," continued the professor, suddenly serious. "Accidents will happen, and you should be prepared for that. Anybody caught misbehaving will leave and never come back." he paused dramatically, then flashed another bright smile. "But apart from that, I see no reason why we shouldn't start straight away! Now, if you will all turn to page fifteen in your textbooks…"

He set them off making a simple potion to cure boils, then went wandering around the classroom giving help and advice. Sherlock flashed his eyes over the Hufflepuff boy as they returned from the supply cupboard. He seemed calm and collected, and the blush from his face had faded quickly. It was embarrassment, then, not exertion, but he must have been running… so used to physical activity.

This thought process had taken less than a second, and for the first time in his life, Sherlock felt the strangest impulse to initiate a conversation.

"Afghanistan or Iraq?" he asked softly. The boy started.

"I – sorry?"

"Your father."

"Afghanistan," he said quietly.

"I'm sorry, it must be hard for you, with him gone, and your mother…" he leaned in closer "I have a salve you can use, it will get rid of the alcohol stains on your trousers."

"Thank you. I'm Watson, by the way."

"Holmes. So have you made potions before?"

"No," said, blushing again. "I'm muggleborn. I've done a lot of cooking though, what with… one thing or another. This doesn't seem too different. You don't exactly seem out of your depth."

Sherlock nodded seriously. "I spent some time in a muggle boarding school, studied advanced chemistry. Muggles are a lot cleverer than a lot of wizards think."

"How do you know about my father?" he whispered. "I haven't told anyone yet."

"Your jacket underneath your robes. It's much too big for you, and has 'military' all over it. It's still in good condition. If he was still alive he'd still be wearing it. I expect you snuck it out of the base when you went to collect his other belongings. The rest of your clothes are slightly shabby, they're cast-offs from the neighbourhood. Your robes are also second hand, you can just see where the shop keeper marked them in the collar. The fact you're wearing old clothes in a new school says 'Hogwarts fund' and 'army compensation' do you agree?"

"Wow."

"What?"

"That was brilliant."

"Really? People normally tell me to piss off."

"Understandable."

The boy added the last ingredient to their potion, which turned the exact shade of blue as described in the textbook. The potion was perfect. Sherlock hadn't expected anything different with him at the reigns, but Watson had required no prompting.

"What would happen," the Hufflepuff mused, "if we added a few more lacewing flies? Surely that would increase its potency."

Sherlock stared in astonishment. "You know I was just thinking that. This recipe is slightly unbalanced."

"Perhaps we should try it sometime, but not here."

"No," Sherlock agreed, ladling some potion into a vial. "In my experience, teachers never like it when students actually use their initiative."

Watson laughed, and Sherlock was amazed, no-one had ever laughed at a joke of his. Then again, he couldn't remember actually trying to make a joke before.

"Very good boys!" cried Professor Slughorn. "Take ten points each!"

"The name's Sherlock," he said as they were packing up their equipment.

"John."

"Nice to meet you, John. I was wondering, I wanted to explore the castle a bit before dinner. Do you want to come?"

"Yeah, okay," agreed John. "I'd love to. I need to learn my way around, can't be late to every lesson."

"Good," said Sherlock as he finished wiping his table. "Let's go then."

XXX

John hadn't been happier for a long time. He had found a subject he was good at, and made a friend outside of Hufflepuff. He found it so easy to talk to Sherlock, he felt that he could tell him anything and trust him completely. As he talked about his father, and his life since Sherlock's eyes were full of, if not sympathy then empathy at least. He quickly realised that Sherlock had remarkable awareness of his surroundings, and that his mind was incredibly sharp. Sharp enough for him to appear to pull knowledge out of thin air. There was something not quite right, though.

"In my last school," said John slowly, "there was a boy who never talked. To anyone. He just sat by himself, he had Asperger's syndrome."

"That's what the muggles used to say about me," admitted Sherlock. "You didn't tell me your mother was a psychologist."

John raised his eyebrows quizzically and Sherlock sighed.

"There's no other way you would have recognised it in me so quickly." He checked his watch. "You hungry? It must be nearly dinner time."

"Um, yeah… do you know where we are?"

"Not far off. The corridors are set out in an arithmetical progression, it's quite simple really."

"If you say so."

"The main staircase should be just around this corner."

Again he was right. John thought that this would quickly become a familiar feeling. The two of them entered the hall together, and said a quick 'see you' before heading off to their separate house tables.

"Where have you been?" demanded Mary as soon as he sat down.

"Went exploring," shrugged John, pulling some shepherd's pie towards him.

"With a Slytherin?"

"Yeah, Sherlock. He's great."

The others exchanged glances.

"John, Slytherin are _never_ friends with Hufflepuffs. Most of them can't even be civil to us."

"Sherlock was," said John. "He seems different to the others."

They all looked around to where the boy was sitting as far as possible from his housemates, picking at his food.

"Perhaps you're right," Mary said. "We'll see."


	3. Chapter 3

**Here is chapter 3. Not everything is as it seems…**

**UPDATE: realised I had dropped an 'r' in 'Moriarty', so here is the corrected version, and thank you to mist shadow for the heads up.**

**Chapter 3**

The first-years quickly fell into a routine of lessons, homework and meals. The second day was just like the first, possibly even better, as John now knew what to expect. In the morning he had his first lesson in the greenhouses, and afternoon brought his first encounters with Professors Binns and Williams. He quickly learned that despite being a ghost, Binns was the most boring person who had ever lived, and left John with the powerful urge to fall asleep. To his dismay, he found that Professor Williams was just as boring, despite being heralded as the most successful Defence Against the Dark Arts teacher in fifty years. When John had asked a prefect why that was, he just shrugged, and cryptically remarked 'he's been here five years'. The only good thing about these classes was that they were both shared with Slytherin, and John sat next to Sherlock. That afternoon, the two went exploring again, but this time they ran into trouble.

They were scouting a corridor near the dungeons when Sherlock suddenly came to a halt, his fingers to his lips.

"There's someone behind that pillar," he whispered. "And the Slytherin Quidditch captain is behind that one. Unarmed, I'd say, but looking for revenge. He's brought one of his cronies to help him beat me senseless. That's very ambitious of them."

"You know how to fight?"

"Yes of course. They'll probably choose the brute strength, should be easy to counter."

"Good. I'll take the Quidditch captain, he's closer. You can get the other one."

"But-"

XXX

Before Sherlock could protest, John had dragged him forwards. The rolled under the arms that tried to swipe them, and Sherlock grabbed the arm as he scrambled back up, and then darted aside as the Slytherin lunged forward. He then yet out a yelp of surprise as he was thrown onto the floor by the small figure. A small tussle ensued, and eventually there was a nasty crack as his head hit the stone floor. Sherlock dusted off his hands. When he turned around, his jaw dropped.

John had finished already, and he stood there, pretending to tap his foot and check his watch in impatience. The Quidditch captain was unconscious, bruises already welling on his head.

"I'm waiting," he said.

"For what?"

"An explanation."

"Huh?" Sherlock was thoroughly confused now. "But he's at least three times your size!"

"My dad was a soldier; do you really think he'd leave me unable to defend myself? No, what I'm waiting for is an explanation as to why we had to beat them up in the first place, not that I minded… most fun I've had in a long time. You can't do this in the muggle world, for some reason they don't like it and arrest you."

"I caused a bit of trouble on the first night – we'd better run, this is a main corridor for Slytherins, and we don't really want to be caught here."

They turned and began running, but John seemed to be finding something amusing.

"What is it?" Sherlock asked in irritation.

"You fight like a girl. You know the theory, but can't seem to execute it; did you learn it out of a book?"

"Maybe."

"Don't worry, I'll teach you properly some time."

XXX

The two Slytherins spent the next few days in the hospital wing. The school was rife with speculation about who had done it, but when the two regained consciousness for long enough to blame Sherlock, the teachers dismissed the idea as ridiculous. By this time, the boys had other things on their minds.

"Have you ever flown before?" John asked.

"If wizards were meant to fly we would have wings," Sherlock remarked dryly. "Flying has never held much appeal for me, I'm not sure I possess the necessary balance."

"Your balance is perfect."

"On the ground, yes. In the air…"

On the Thursday afternoon, they were met by Madame Pomfrey on the main lawn.

"Hello first-years! So we've got the Slytherins, Hufflepuffs, Ravenclaws… come along Gryffindors, hurry up, you're late!"

They all glanced back to stare at the latecomers, and John walked straight into Sherlock. He was stood stock still, staring back the way they'd come. John followed his gaze. There was an intricate carving on the wall of Hogwarts that the first years had missed in the dark of the first night. In huge letters at the top was 'Heroes of the Second War', and underneath…

"Are those names?" asked John, but the other first years had all surged forwards. Madame Hooch sighed, this happened every year. The familiar sounds of surprise and sadness washed over her.

"That was my uncle."

"Grandfather…"

John stood back to let the other children get closer, he knew nobody on that wall. He noticed a lot of Slytherins do the same. Then he saw Sherlock.

The little colour the boy had had drained from his face, turning him a ghostly white. He was shaking.

"Sherlock-"

Suddenly he jerked to life, and took off back towards the castle. John stared at the wall again, and spotted the name Sherlock must have been looking at.

_Caius Holmes_

"Jesus," he breathed. "Sherlock!"

But the boy had disappeared, students were still recovering from when he must have violently pushed them out of the way.

"I'll go," he told Madam Hooch. Not waiting for a response he ran after his friend.

Madam Hooch was now completely bemused. In the last five years, a lot of people had broken down in tears in front of the wall, but no-one had ever just run off, and definitely not a Slytherin. Then there had been that Hufflepuff running after him, surely they weren't friends. She called all the other children to attention.

Meanwhile, John was running in circles looking for Sherlock, it didn't help that he had no idea where he would have gone. He leant against a wall rubbing his eyes. _He needed to find his friend._

To his shock and amazement he tumbled backwards into a hidden passage way. He yelped as it sealed himself behind him, but a torch close by flared to life, revealing a narrow passageway that twisted and turned. Unable to go back, he hurried forwards, coming out somewhere in the dungeons. The pendant against his chest flared with warmth, and he followed his instincts through the dark passageways.

XXX

Sherlock had fled with no real direction or purpose, and it was a surprise when he found himself in the shelter of the dungeons. He sank down into an alcove, trying to calm his breathing. He was still shaking, and curled into a ball in an attempt to control himself. He wondered vaguely what his body was feeling. With the provocation he would have said sentiment, but he knew that wasn't it. He sighed. Why did it have to be here?

"Sherlock,"

He almost jumped out of his skin. John had just appeared next to him. How on earth had he found him down here?

"Are you alright?"

"Fine," he replied curtly. "Never been better."

"Sherlock…"

"Why did it have to be here?" he hissed. "I thought I was free, but oh no, 'Heroes of the Second War'! Hero! Damn Harry Potter to the dungeons, Voldemort did me a favour."

"Voldemort?"

"Stupid bastard deserved what he got."

He buried his head in his hands, losing control completely.

XXX

John looked on in horror as Sherlock started hyperventilating. He was clearly having some sort of panic attack.

"Come on," he whispered. "We can't stay here."

He manoeuvred Sherlock into a standing position, surprised to find he was much stronger that his stature suggested. However he was also thin. Very thin. His wrists especially looked as though they could snap at any moment.

"There you are," said a relieved voice behind them. They both whirled around and Sherlock toppled. The stranger caught him, and set him upright. As he did so, there was a flash of a prefect's badge.

"I've been looking for you everywhere."

Sherlock glared at the Ravenclaw. "Piss off."

The other boy took in his trembling form.

"Take him to Mrs Hudson," he instructed. "Hospital wing, fourth floor. We need to get a calming draft in him."

"Okay, give me a hand."

The boy shook his head. "He won't respond to me, besides, I've got to let the others know I found you."

A second boy rounded the corner, a Gryffindor. He had a head boy badge pinned to his robes.

"You got him, Mycroft?"

"Yes, give this kid a hand will you?"

"Sure," the head boy hoisted Sherlock into his arms.

"James Moriarty," he said. "Come this way."

John followed him back out of the dungeons, blinking as they stepped into the bright light of the entrance hall. After his eyes cleared he could see their companions properly.

Moriarty was tall and strong, with golden hair that fell onto his shoulders. The other boy, Mycroft was even fatter up close.

"Nice to meet you, Watson, I'm Mycroft Holmes, Sherlock's brother."

"How do you- never mind. Yes, I'm Sherlock's friend."

Mycroft narrowed his eyes. "My brother doesn't have _friends_."

"Says who?"

"Sherlock managed to create chaos within Slytherin house on his first night. Going out and making friends with a Hufflepuff would be suicide."

"So?"

"Here we are!" announced Moriarty, setting Sherlock down, and draping one of his arms over John's shoulder. "Take him in; I've got to go now. Come along, Mycroft!"

John led Sherlock into the hospital wing, and sat him down on a bed. Mrs Hudson came rushing out of her office.

"Well now, what have we here…"

In the light of day, Sherlock looked even worse than he had in the dungeons. His skin was almost translucent, and had a greenish hue.

"It was the war memorial. His brother said something about you giving him a calming draft."

"Of course, I'll be right back."

As she hurried back into her office, John turned his attention to Sherlock, who was on the verge of fainting. He seemed to be going into severe shock, but that made no sense, unless…

Mrs Hudson returned with a pale purple potion which she forced Sherlock to drink.

"What happened?"

"I'm not sure. He saw his father's name on the memorial, and then…" he gestures towards Sherlock, who was now unconscious.

"Are you his friend?"

"Yes Miss."

"It seems to be a bit of a severe reaction. Either there's something deeply psychological, or- oh, hello."

Sherlock had weakly opened his eyes.

"Now, I just need to- no, don't sit up! I've got a few questions, that's all. Now," she picked up a clipboard, "when did you last have something to eat?"

Sherlock frowned. "What day is it?"

She lowered her clipboard, obviously appalled.

"Well," she said icily. "I think we've found the root of the problem, haven't we?"

She swept away, and John took the chair next to Sherlock's bed.

"You idiot!"

"Huh?"

"You haven't eaten today? In a few days? No wonder you're here, you look like death warmed up!"

Sherlock shrugged. "The brain's what matters, anything else is just transport. I never eat while I'm thinking, it slows me down."

"But you think _all the time_! Jesus."

Mrs Hudson reappeared with a plate of sandwiches, and a few glasses of pumpkin juice, which she deposited on Sherlock's bedside table with a clunk.

"Eat all of that, and then you can go."

"But-"

"No buts. And you, make sure he eats it. Please excuse me."

She left again, out into the main corridor.

"You know what she's gonna do now," said John. Sherlock nodded.

"Tell all the teachers to spy on me I expect." He swung himself upright, and tried to stand up. He swayed dangerously, and John forced him back onto the bed.

"Hmm, still a bit dizzy- hey!

John had stuffed a sandwich in his mouth.

"Oh, well, said Sherlock miserably. "It was probably my day to eat anyway."

He finished the food under John's watchful gaze, and then got up again. This time he was steady.

"Shall we go?"


	4. Chapter 4

**Time to answer a few reviews…**

**Thank you to everybody who's found time to give me their opinions.**

**Tikky Mikk, a house-elf information network was always on the cards for me, but won't feature in this story.**

**Mist Shadow, I think introducing Sherlock to Luna would be a very bad idea! Certainly a thing to consider for later on, but personally I think it would all end in tears! And thanks again for pointing out my mistake in chapter 3.**

**Chapter 4**

"Tell me about your father."

Sherlock glowered at the woman in the chair opposite. He had been hauled out of potions to visit the Headmistresses office, and now they were attempting to psychoanalyse him. Well, two could play at that game.

"What's your earliest memory of him?"

Sherlock stayed silent. The woman was beginning to lose her patience. This was fun.

"What did he look like?"

Still waiting. She sighed, and rested her notebook on her knees.

"Look, there's no point in me being here if you're not willing to respond. Just tell me something."

"Anything?"

"Yes!"

"Your fiancée's gay, he's just marrying you for your money."

"I – what?"

"He's also allergic to your cat. You don't seem to be too keen on marrying him, but your mother's insisting. Probably because he's got the 'purest' blood out of Azkaban. Your brother, now, that is interesting, did you know he's been dealing drugs? No, probably not, no matter he'll be caught soon anyway. Now, the end of your quill suggests that your job stresses you out, so if I were you I'd get back to St Mungo's, and finish all that paperwork. It'll certainly be more constructive than making me miss my potions class."

He looked back at the woman to find her crying. Job well done. He got out of the chair, and made to leave.

"Oh, and don't bother coming again, I won't be so nice next time."

Dinner had already started when he got back downstairs, but he managed to find a seat away from the others. He pulled a plate of spaghetti towards him, but wasn't really in the mood to eat it.

"Sherlock!"

John was approaching. He looked… guilty.

"You knew! You knew they were going to set a therapist on me!"

"Perhaps. How did it go?"

"Mission accomplished. She won't be coming back again."

"Oh God, what did you do?"

"Sat tight and silent, then told her her life story."

"Did she cry?"

"Of course."

"Jesus, Sherlock…"

"What? She was asking me questions, it was self-defence!"

"She was only trying to help."

"I don't need help."

"Oh really? Then why aren't you eating?"

"I am-"

"Don't try to kid me."

"But-"

"Sherlock Holmes, you get that eaten _right now_!" he hissed, banging his fist on the table. Sherlock admitted defeat, and ate his dinner.

XXX

"John what's going on between you and Sherlock?"

John looked up from his herbology essay to Mary, who was curled up at the other end of the sofa.

"What do you mean?"

"You know what I mean."

"He's my friend."

"Really? Is that it?"

"Of course – what are you trying to say, Mary?"

"Nothing, I guess, it's just, Holmes doesn't seem to have any other friends."

"He's not really the most sociable person."

"Then what makes you special? Slytherins only usually have friends because they want something from them; it's been like that for centuries. Before I came to Hogwarts, mum told me that the last recorded friendship between a Hufflepuff and a Slytherin was Ted Tonks and Andromeda Black, and when they got married she was disowned."

"I'm not gonna marry him. Besides, Sherlock's whole family was in Ravenclaw, he's not your average Slytherin. Who says there's such thing as an average Slytherin anyway? Look, you don't know the state I found him in on Thursday, and I'm not going to tell you because I promised I wouldn't. But I will tell you that his brother refused to help. That's his family life right there. If I didn't know better, I'd be inclined to say there's been abuse in the past, if not physical then certainly emotional, and there's nothing we can do to help. McGonagall asked a therapist to talk to him, but his instinct was to make her cry!"

Mary chuckled.

"It's not funny! He's cut himself off from everybody else! I just don't want him to drift too far away."

XXX

"What are you reading?"

Sherlock glared at the girl over the top of his book. He did not appreciate interruptions. Unperturbed, the girl settled herself on the seat next to Sherlock, flicking her golden hair, and fluttering her long eyelashes in a manner that was probably supposed to be alluring. It was all too easy to ignore, but there was something odd about her.

"What's your name?"

"Lucy Fazir. I already know who you are, Sherlock Holmes."

"Why are you here talking to me?"

"What-"

"By the time we've finished school, I expect you'll have been around the common room a few times."

"What do you take me for?" she asked angrily. "Besides, the others don't seem to notice me."

"No," said Sherlock. "They don't, do they? I wonder why that is?" he frowned, examining the girl more closely. "There seems to be something blocking me, like I don't _want_ to see you, which is perfectly true, I'm afraid. It's like a magical shield. I can't tell who's casting it, though."

"A shield?"

"Yes," he turned back to his book.

"A Study of Disabling Drafts? Where did you get _that_ from?"

"Acquired it from my brother," he glanced up. "Goodbye?"

"Fine," she grumbled. "I know when I'm not wanted."

"Yes, good, I'm glad somebody does."

XXX

_SEARCH CONTINUES FOR MISSING GIRL!_

_Jayne Lexis, aged fifteen, disappeared from Hogsmeade during the summer of her fifth year at Hogwarts. She was celebrating the completion of her OWL exams with friends when she vanished from the crowded street. All the Aurors ever found was her wand, which had been used to carve the word 'Ultio' (Latin for 'revenge') into the wall of the three broomsticks. The ominous message, combined with the complete mystery of her whereabouts, is ensuring that even top Auror Harry Potter's hair is standing on end._

"_We're not saying it's a death eater attack," he told a Daily Prophet reporter, "but we're not ruling it out either…"_

John lowered the paper, staring at Peter.

"And no-one ever told me about this before?"

"Relax," he said. "It's not as if she disappeared from inside the school. All the Hogsmeade trips for the older students have been suspended for now, that's why the upper years are all so hyperactive."

"Respectable family, the Lexis's," remarked Mary. "It was rumoured that they were descended from Rowena Ravenclaw herself."

"One of the founders?"

"Yeah."

John looked routinely up at the Slytherin table, and sighed.

"I'll see you in class," he told the others, getting to his feet.

"He's not eating?"

"Yeah."

"I don't know why you bother."

John slid onto the bench opposite Sherlock.

"What is it this time?"

"Nothing really, it's just… Jayne is my cousin."

"What? Were you close?"

"No,"

No surprises there.

"But we were still – you know – related. What is that, is that sentiment? By the way, this is Lucy."

John jumped as he noticed the Slytherin girl for the first time.

"So sorry, didn't see you there."

"That's okay."

"Anyway," cut in Sherlock. "I've got to go to the library."

"Sherlock…"

"Please, John," he said. "Just this once."

"Alright."

He sighed in relief, abandoning his full plate and walking away, leaving John sat with Lucy at the Slytherin table.

OOO

"John? John! Wake up!"

"Someone get Mrs Hudson!"

"John, can you hear me?"

John wrenched himself awake, gasping and spluttering.

"Dad…"

There was a blinding pain in his head, and he was tossing and turning, trapped in his blankets. He didn't realise he was yelling until he felt a pair of cool hands on his face.

"Watson? Mr Watson?"

"Mrs Hudson," he gasped. "My dad… no!"

"He's burning up, Pomona," he heard her say. "Completely delirious. Mr Carson, can you carry him to the hospital wing?"

"Of course, Maria."

"Keep him in his blankets, that's it…"

He felt a pair of strong arms lift him up. His pendant slid slightly against his chest.

"It's alright, lad," said a deep voice in his ear. "You're gonna be okay, you're gonna be well looked after."

John tried to struggle, but his limbs weren't responding, and it wasn't long before he had slid back into unconsciousness.

XXX

Sherlock, as usual, was the first person into the DADA classroom, and took his usual seat at the back with anticipation. He hadn't seen John yet this morning, and he couldn't wait to outline the new narcotics identification method he'd been working on. However, when the Hufflepuffs arrived in their usual huddle, John wasn't with them. He didn't turn up late, and Professor Williams started the lesson without him. So the teachers knew, something was wrong. He examined the Hufflepuffs. They all looked worried, but the boys were exhausted. Something had happened during the night. After the lesson, he decided to do the unthinkable, and approach the others. He reached the girl first.

"Um – excuse me,"

"He's in the hospital wing."

"I thought so, ta."

He fled before she could speak again. That was quite enough interaction with a girl for one day. As he sped around the corner, he tripped, and found himself sprawled in a heap.

"Hey, watch where you're going!"

"Sorry, Lucy." Out of courtesy, he helped her up. He still couldn't seem to see her properly. As she righted herself, he spotted a leather string around her neck, and swiftly plucked it out of her robes.

"What's- oh!"

It was a glowing green amulet, a clear emerald with a snake engraved on the surface. It exuded magic and power.

"Ah."

"Give that back!"

"There's your shield."

"What?"

"Trust me, take that off, and everybody will notice you."

"But…"

"Take it off!"

She complied, and her presence exploded onto the corridor.

"Better?"

She nodded. He smiled smugly.

"Good luck with the others."

OOO

Dinner that night was a more rowdy affair than usual. Sherlock hadn't even noticed that it was Halloween, but everybody else was going crazy over it. After a big feast, there was 'entertainment' provided by the ghosts, but Sherlock didn't pay much attention. The room appeared to be spinning, and it was very distracting. With a start he realised everyone was getting up to leave.

"Are you okay?"

It was the Hufflepuff girl from earlier.

"It's just, I know John usually-"

Her words were lost as Sherlock tried to stand, but instead fainted away.

XXX

There was a dull orange light burning through his eyelids. John groaned, and nearby he heard anxious footprints.

"I… what… where am I?"

"Take it easy, just lie still."

John blinked, attempting to clear his vision. He was in the hospital wing, Mrs Hudson by his side. And fast asleep in the next bed…

"Sherlock," he croaked.

"That's right. He'll be fine. He's just got the same as you, some sort of muggle infection. It must be contagious."

John tried to sit up, but didn't have the strength.

"What happened?"

"You've been ill," she said again patiently. "But you'll be better soon. Just sleep."

OOO

"Look at the pair of you," laughed Mary a few days later. "You do everything together!"

Sherlock mumbled incoherently.

"Have I missed much?" asked John, rubbing his head.

"The Halloween feast, that was good fun, and I expect you'll miss the Quidditch match tomorrow. Oh well, there's always the next one."

"I expect so."

OOO

The next afternoon there was a moan from the next bed, and Sherlock sat up, his hair on end. He looked so confused and lost that John had to fight not to laugh out loud.

"What's going on? What day is it?"

"Saturday," he told him.

"What? But that's… that's…"

"Don't worry, you'll feel better tomorrow."

"Sure."

"John!"

The door to the hospital wing was flung open, and Mary ran inside.

"John!"

"Sh!" hissed John, indicating a still dazed Sherlock.

"No – it's okay," said Sherlock, lying back down.

"How was the match?"

"It got called off," she perched on the end of John's bed. "There's been another disappearance."

"What?"

"David Jones, a Gryffindor chaser. He didn't show up to the match. A few hours ago, they found his wand and another carving on the wall."

"So exactly the same as…"

"Jayne Lexis in the summer. Yeah. So now everybody's a bit edgy. Actually, curfew's been moved forwards to six o'clock, so I can't stay long."

"Was it the same word? The carving?"

"Yeah, 'Ultio'."

"Latin for revenge," muttered Sherlock. "It's a red herring."

"Huh?"

But Sherlock had already fallen back to sleep. It wasn't long before Mrs Hudson hurried out of her office to shoo Mary away.


	5. Chapter 5

**Okay, this is my first attempt at a grand scale deduction. You will also see a different perspective on two popular characters. Feel free to comment, but be nice? Please?**

**Chapter 5**

The two boys emerged from the hospital wing on Monday morning to a school in uproar. The girl had been right when she said people were edgy. The teachers were practically dancing around on their tiptoes. Sherlock could tell that there were Aurors in the shadows, and cursed the ministry's stupidity. Trust them to give the students a false sense of security. He was itching for a chance to examine the crime scene himself, but the whole corridor had been closed off. After a while though the school started buzzing, there were rumours flying around that Harry Potter himself was in the school. When the prat himself actually appeared at lunch time, it took next to no effort to sneak out of the great hall unnoticed.

The door to the corridor was locked, but that wasn't a problem for Sherlock.

"Alohomora!"

He slipped inside, and took a cursory glance around, memorising every little detail. It was obvious what had happened.

"Who are you?"

He cursed under his breath. When he turned, it was a shock to discover he was standing in front of the two most famous Aurors in the squad. Not that it mattered, it didn't make them any less moronic than the rest of them.

"Just looking, I wanted to see for myself. Don't worry, I haven't touched anything. I could see enough from here. I wonder which drug he used…"

"Get out of here, kid," said the red head. "Your head of house will be informed of this. Typical Slytherin."

"Relax, Ron," said Potter. "Do you remember when we were his age?"

"We didn't break into a crime scene."

"Something chlorine based, at a guess. So, knocked him out there, and then lifted him, no dragged him first approximately… twenty feet. He put up a fight. Well, Quidditch player, I guess he's strong. Then…"

"Whoa, hold up," said Potter. "What are you saying?"

"He was kidnapped."

"We know that already, thanks," said Weasley, rolling his eyes. "Now get out."

"No, wait," said Potter. "What else have you got, kid?"

He screwed up his nose at the word _kids_, but let it pass. "The kidnapper was around six foot tall, with longer legs. Jones was a tall kid though, so he must have been strong, a man. He was wearing dragon-hide gloves, and he was left-handed."

"Left-handed?"

"Yes, obviously. Took him down _that_ secret passage there, so he had inside knowledge of the school…" he glanced back up and caught their expressions. "Oh, and perhaps I should mention that _I_ didn't take him."

"But why would we-"

""It's a perfectly logical assumption. Strange kid turns up, dissects the crime scene beyond your capabilities. I tried to help out in muggle London once, and managed to get myself arrested by their secret service, but then it's hardly my fault that what _looked_ like a simple murder was actually an assassination… Well don't just stand there gawping, don't you have anything constructive to add? I was told that you two were part of the trio that brought down Voldemort, you must have at least a pair of brain cells between you."

Weasley made to grab him by the scruff of the neck, but he dodged him.

"I'll come quietly."

A few minutes later the ginger was banging on the door to the headmistresses office.

"Oh, hello Harry – Mr Holmes? What are you doing here?"

"Wait outside," ordered Weasley. Sherlock obeyed him, grinning.

"What is it, Ron?" asked Professor McGonagall, her voice slightly muffled by the door.

"We found the kid in the fifth floor corridor. He told us everything about the kidnapper, then proceeded to insult our intelligence."

"What?"

"It was quite funny," Potter admitted. "He's obviously very… bright."

"Little sod," Weasley muttered. Sherlock sniggered. "He may well have been making it up. I mean, he said the kidnapper was left-handed, but when asked, he said it was obvious!"

"Then why don't you ask him to explain himself?" asked Professor McGonagall. "Mr Holmes!"

Sherlock entered dutifully, and sat in the wooden student's chair.

"Explain yourself."

"What would you like me to say?"

"Start at the beginning," said Potter gently. "You said they'd been drugged."

"Yes, there is a residual chlorine odour in the air, very distinctive. There are little scuff marks on the floor from where Jones struggled, but only for twenty feet, so he was unconscious in seconds. The scuff marks also give an indication of the kidnappers stride length. It also reinforces the evidence for him being left handed."

"Yes about that…"

"The darkest marks left by the shoes are on the left; his legs were swung upwards to the right while the kidnapper supported the heavier weight of his body in his left arm. The grooves in the wall are slightly uneven, the deepest part again being to the right. The wand was being held and angled from the left, hence – oh, Merlin."

A blinding pain flashed behind his eyes, and he buried his head in his hands.

"Are you alright?"

"I'm fine," he gasped. "I've been ill, that's all. Still got a bit of a sore head."

"Perhaps you should-"

"I am _not_ going back to the hospital wing; I've spent enough time in there already."

Potter chuckled. "I know the feeling. I'll take him to his common room, Minerva."

"Just one more thing," she said. "Mr Holmes, if you could wait outside."

As soon as he was gone he heard her turn to the other two.

"Whatever you do, don't give the boy any trouble for disturbing your crime scene, Jane Lexis is his cousin."

"Oh," said Weasley.

"And he's not like other children. His senses… well that door has a _muffliato_ charm on it, but I expect he can hear every word I'm saying."

"But what if it _was _him?" asked Weasley.

"Impossible. He's been in the hospital wing for days."

"He's certainly very intelligent," Potter remarked. "You have a star student there."

"Indeed. The other teachers tell me his knowledge is at least fifth year standard, but that he refuses to do any work which he believes is beneath him… quite a lot at this stage. I told them to let it slide for now. Did you know he's a direct descendant of Ravenclaw?"

"Explains a lot."

"But then why is he in Slytherin?" asked Potter.

"Exactly," sighed McGonagall. "We may never know the answer to that one."

OOO

"You're different to how I thought you'd be," said Sherlock as Potter walked him back downstairs. "Your public profile isn't exactly flattering. I was under the impression you were a bit of a tosser."

"Thanks a lot."

"You're welcome – wait a minute that was sarcasm."

"Of course."

"Not every day you find an Auror who's open-minded."

The man shrugged. "You spend a year on the run; you kind of learn to accept the impossible."

"No, you learn to accept the improbable. Trying to accept the impossible is a mistake only amateurs make. Thank you for humouring me, Mr Potter, and enjoy your lasagne tonight."


	6. Chapter 6

**There seemed to be a problem with this update the first time around, so let's try again.**

**Hello readers, time to answer a few reviews…**

**Tikky Mikk, I think one day he will meet the little Potters, but they will be too young to have any kind of role in the story line. However, I have just started writing the sequel to this story, and a seven year old Teddy Lupin will feature quite heavily!**

**Mist shadow, ordinarily I think that Ron would be a very good Auror, but he is definitely the type of person Sherlock would despise.**

**And thank you to everybody else, you've all been so nice!**

**This next chapter is mostly a filler, as I wanted time to introduce my 'younger brother' version of Harry Watson. I also did not want to just gloss over Christmas.**

**Chapter 6**

The Christmas holidays were approaching, but John was finding it difficult to get into the right spirit. A feeling that was, unsurprisingly, shared by Sherlock.

"I'm not going home," he had said flatly. "Christmas is hell in my household, has been for a long time. I take it you're going back."

"Of course. I can't expect Harry to cope with mum on his own over Christmas."

"But why do you have to be the one to help?"

John stared at him.

"Not good?"

"He's my brother!"

"But you clearly don't want to go."

"Excellent deduction, Sherlock."

"Ta, but I still don't understand-"

"Well you wouldn't, would you?"

Sherlock turned, alarmed at the anger in his friend's voice, but John had had enough.

"You don't care. You don't know what it's like, to scrounge for money to get enough to eat, or to wake up every morning knowing your mother's in a gutter somewhere on the other side of town, or to have to be the one who…" he stopped abruptly.

"John? What is it, what did you do?"

"I'd forgotten," he said quietly. "How could I…"

He turned on his heel, and fled back down the corridor. Sherlock hurtled after him, but when he rounded the corner, John had vanished. That was one of the largest corridors in the school, and John had only been a few feet ahead of him. How had he disappeared so quickly? He sped back to the hall, where lunch was still in session.

"Morston!" he called.

"Holmes?"

"Have you seen John?"

"Not since you two left ten minutes ago."

"He's gone, he just ran off. I think I upset him somehow."

"Come on, we'll let Professor Sprout know."

XXX

John watched the owl fly over the forest and out of sight. He stood there a while, enjoying the feel of the icy air against his face.

"John?"

Mary had found him, and he felt a comforting hand on his shoulder. He shrugged it off, he didn't deserve her sympathy.

"John, what's the matter?"

"Leave me alone!"

"John…"

"Go _away_!"

"No."

She folded her arms obstinately. He avoided her eyes.

"Tell me what's wrong."

"You'll hate me."

"Why?"

"Everybody says Hufflepuffs are loyal," he mumbled. "But I betrayed them, Mary, I betrayed my family."

She reached out and took his hand, leading him away.

"A lot of muggleborns feel conflicted about coming to Hogwarts."

"I went to social services," he whispered. "I went, and I told them all about mum, and they said they'd help, but Harry's only ten, and I told him not to write because of the owls. He could be in a home right now, and I have no idea…" he trailed off. "I'm going home these holidays, and I have no idea what I'm going to find."

"Oh," said Mary. "I'm so sorry, John."

"It's okay."

"No, it's not."

"No," he agreed. They were crossing the lawn when Sherlock emerged from the main door.

"Nice chat with your girlfriend?" he smirked. His tone set John on edge. "I don't see why you're so bothered," he sniffed, "couple of muggles. Yaxley said they lived like animals."

"Holmes!" Mary shouted, but John lost it completely, swinging his arm in an attempt to punch him. Sherlock, however, sparred, and laughed tauntingly at him. Soon they were fighting properly. Sherlock had been practicing, and John was surprised to find the first worthy opponent since his father.

"What do you two think you're doing?"

Mary had obviously gone for help, and returned with Professor Sprout. The two ignored her, and John flipped Sherlock onto his back.

"Yield?" he asked threateningly.

"Yield," he gasped. Then he grinned. "Feeling better?"

"Yes," he admitted.

"I'm sorry about what I said; I was just trying to provoke you. Although next time you're upset I'll encourage you to take it out on a tree, perhaps that way I'll have fewer bruises."

"Thanks a lot."

"You're welcome."

"That was sarcasm."

"Oh."

"But thanks anyway."

"Dinner?"

"Starving."

And the two set off to the castle, leaving an exasperated Mary, and a confused Professor Sprout in their wake.

OOO

In the end, John asked Sherlock to go to his house for the holidays. Sherlock hesitated, but eventually agreed, on the proviso that he would help pay for his living costs while he was there. His mother had been easy to persuade, from her letter John was sure she was glad to get him off her hands. Sherlock said nothing to contradict this. On the last day of term, he managed to talk Sherlock into sitting with him and his Hufflepuff friends. To his surprise Lucy also joined them. She seemed to have developed an attachment to Sherlock, but of course the boy himself was blind to this, and ignored her for the whole journey. He didn't talk to anyone else either, and John found himself wondering what sort of Christmas he had managed to set himself up for.

XXX

John's home was similar to what Sherlock thought it would be. It was small, slightly shabby, and poorly kept, but Sherlock didn't say this. The place was just big enough for four, and Sherlock found that he actually enjoyed the compactness of it. The family manor was enormous and cold, and all in all there was just too much _space_.

They took a cab from King's Cross, but when they got in, Mrs Watson wasn't there.

"Harry?" shouted John, a flash of panic crossing his eyes. "Harry are you there?"

A small figure shot out of the nearby kitchen, and buried its head in John's chest. He hugged the boy back tightly, and Sherlock found himself feeling awkward at the overt display of brotherly love.

"Thank god you're alright," John sighed. "I was so pleased to get your letter. Forget what I sadi before, next term write, okay?"

"Okay."

"Where's mum?"

"Out."

The two exchanged glances. John stepped back, and Sherlock could see him examining Harry closely.

"I'm fine," insisted Harry. "Social services helped a lot."

"I'm sorry I did that…"

"No it's fine, really. You were right; we should have done it ages ago. They did take me away for a few weeks, but she only goes out occasionally now."

"Alright. Harry this is my friend Sherlock."

Sherlock then had the unnerving experience of being the one scrutinised as Harry turned his soft brown eyes on him. Apart from the eyes, he looked so much like John.

"Nice to meet you, Harry. Has John told you much about Hogwarts?"

"Not much."

"Well, I think you'd better go into more detail, John, he'll need it in September."

"What? Harry's a wizard?"

"I think so I'm ninety-two per cent sure. When are you eleven?"

"Not until April."

"Well, I'm afraid we won't know for sure until then."

"Let's get our trunks upstairs," said John. "And then I'll make us some food."

"I can-"

"No, Harry, this is your holiday too. You've been on your own for three months. Besides…" Sherlock was alarmed at the sly grin that crossed his face. "I'm sure Sherlock would _love_ to play with you."

"Just one more thing," said Harry. "Mum began c-clearing out d-dad's stuff. Sh-she made a big p-pile of things in your room to chuck. You might want to check it out."

"Alright," he ruffled the other boy's hair. "We'll be back down in a minute."

"'Kay."

Sherlock pulled his trunk up the stairs after John, and helped him pull out the collapsible bed. Then they turned to examine the pile.

"Is that a violin?"

"What the hell's that doing there? And these records… she's mad. She's bloody mad. All this stuff was really special to dad."

"Perhaps that's why she wants it out."

He pulled the violin out of its case, and began plucking the strings.

"You play?" asked John, as he absent-mindedly tuned it.

"I had a lesson once, but – but _father_ didn't approve, so my _dear mama_ refused to let me have one."

He dusted some resin onto the bow, and drew it across the strings.

"You don't mind, do you?"

"Nah, none of us can play. Right, I gotta find a place to hide these…"

XXX

Apparently, John's house was odd, and that was quite a lot coming from Sherlock. He knew that Sherlock had spent some time at a muggle boarding school, and so coped with the electrical and muggle items quite well. Fortunately his mother didn't appear much, she spent as much time as possible out of the house. She seemed to be avoiding him. Not that he minded, he was only here for Harry really.

Christmas was a quiet affair. John and Sherlock mostly got practical presents, clothes and books. John got some sweets from his friends, and a 'quality stationary kit' from Sherlock. He had to laugh at that, but he was pleased that it included a fountain pen. Writing with a quill was just painful, of course Sherlock would notice that.

"It's charmed to have everlasting ink," he said. "It's default is black, but if you want another colour you just have to tell it."

John had decided to give Sherlock his father's violin. At first he had refused to take it.

"It was your father's!"

"He's dead. It's not going to be used. All it will do is collect dust."

"But-"

"You know there's no point in arguing, Sherlock. You're the one who moans that Hufflepuffs are so stubborn."

"What's going on?" said Harry's sleepy voice from the door. He crossed the room and got into John's bed. To his great surprise, Sherlock tossed him a package.

"Your brother is trying to give me your dad's violin."

"I know."

"You suggested it."

"Yeah," he said sheepishly. He had grown used to Sherlock over the past week.

"And your mother?"

"She won't even notice. I did ask her, but after she's been out she just says yes to anything I say. I took it as permission."

Sherlock chuckled. "John you may have a snake for a brother."

John just rolled his eyes. Harry laughed, he had heard all about the house system. He tore the wrapping off Sherlock's gift and gasped. It was a selection box of magical sweets.

"Don't eat them all at once."

OOO

John hugged his brother tightly as Sherlock loaded their trunks onto the train.

"Stay safe," he told him. "I talked to Mrs Turner next door, and she promised to keep an eye on you. Louise's number-"

"Is taped to the fridge, and if mum puts me in danger, I shouldn't be afraid to let them take me," he recited. Then he faltered. "You won't be coming back at Easter."

"No, I'm sorry, but I don't think mum likes magic."

"She was fine until you came home."

"Just don't tell her about – about the possibility of you being…"

"Got it. Anything else, sir?"

"Little brat."

A whistle resounded down the platform, and Harry started crying.

"Look after yourself!" cried John, clambering onto the train, and leaning out the window. "Don't forget to write!"

XXX

Sherlock watched John's cheerful façade fade as they got further away from the station. He knew that if he entered the compartment he would have a crying mess on his hands, and had no idea how to cope with that. So instead he sighed, turned on his heel, and went in search of the Mary girl.


	7. Chapter 7

**In response to a review, yes in the Sherlock TV series Harry is John's sister, but in the original stories (which are just as amazing) he is a brother.**

**Only a few chapters of this fic left now, and then I will start writing the next one!**

**Chapter 7**

Sherlock was immensely relieved to be back at school. Being unable to perform magic was tedious, and he hadn't been able to run his experiments. The only downside was that he had to see his brother again, but at least they weren't in the same house. Since returning, he had discovered that rats still secreted saliva after death, chlorine based drugs knocked him out for at least ten minutes, (though the resulting headache lasted several hours), and violin music really annoyed his fellow Slytherins. Therefore, he played it as much as possible.

The months passed, and before he knew it spring was upon them, with no more kidnappings, or clues about the kidnapper. He was just leaving the library in the middle of April when Professor McGonagall's voice echoed down the corridors.

"All students will return to their dormitories. All teachers please report to the charms corridor."

Sherlock grabbed John before he could react.

"Sherlock, where – we can't go there!"

"I just want to see."

"But why are you dragging me around this way?"

"So it looks as if we were on the way to our dormitories!"

"Oh, I see."

They bolted around another corner, and skidded straight into Professor McGonagall.

"What are you two doing?"

"Going to our dormitories, Miss," replied John, the very picture of innocence.

"Yeah," said Sherlock, but then his mouth dropped open in horror. "Lucy."

"What?"

"Lucy's been taken," he pointed to the Professor's hands. She was holding a bright green pendant. "That belongs to her. May I…"

He took it from her, and turned it over miserably in his hands. At this point the other teachers arrived, accompanied by Harry Potter and Ron Weasley.

"Minerva who-" began Ron, then his eyes fell on Sherlock. "Oh no, not him again."

"Lucy," he sighed again, before casting an eye over the scene. "Same person same method. But this pendant…" he put it right up to his eye, examining it. Then it hit him. "Merlin's pants," he gasped. "Stupid, stupid, stupid. Perception magic, I should have known, it prevented me from seeing the truth. Professor, my cousin Jane had a blue pendant like this, and I'll bet you anything Jones had a red one."

"Is it significant?" asked Potter.

"You bet it is," said Sherlock. "It shows-" but he choked on the words. "I – can't…"

"Tongue tier," sighed McGonagall. "He can't spill any secrets."

Sherlock took a deep breath, and thought carefully about his words. When he hit a loophole his tongue unrolled. The jinx was triggered by one word.

"Three pendants," he said. "A green one, a blue one and a red one. I think there'll be a yellow one out there too. Professor Sprout, you might want to keep an eye on your Hufflepuffs. They're not just necklaces, they're symbols, and have special powers, but I don't think I'd be able to tell you what those are. But seeing as this is engraved with Slytherin's crest, it shouldn't be a difficult deduction."

"Hold on," said Harry, and Sherlock was pleased to see he was catching up. "Slytherins line died out with Voldemort."

"It's impossible to be sure," said Sherlock. "Most purebloods can trace their family back to the founding of Hogwarts, but in the Slytherin-" he choked again. "Okay, okay, I can't say it directly. Let's just say there's a spot in the middle ages where everything goes a bit foggy. I expect Lucy had no idea what the pendant really was. With any luck, the Hufflepuff won't be school age; it's a huge coincidence with three necklaces here as it is."

"So we can find out the next victim."

"I think we can find the kidnapper," said Sherlock. He pointed to the floor underneath the carving, where there was a smudge of mud in the shape of a boot.

XXX

John watched with amusement as Sherlock 'requested' both him and Harry Potter to accompany him to the potions lab. He knew by now that Sherlock performed best with an audience, and the Potter man seemed to have met him before. All the same, he couldn't help feeling like a loose end, and he was sure Potter did too.

"Are you the same Harry Potter that the others talk about sometimes?"

"That's me," he admitted. "So are you a friend of Holmes'?"

"Yes, and before you say anything I am perfectly aware that he's a Slytherin."

"I wasn't going to say that," said Harry. Behind him Sherlock nodded in assent.

John smiled, and picked up Lucy's pendant. He had the strangest feeling he'd seen it somewhere before.

"Sherlock…"

"Not now, John!" he snapped. "Okay, so we've got dust from the corridors, mud from both the grounds and the forest, some old potions spillages, and… hello, what's this?"

He frowned, and gazed intently at whatever it was that had caught his attention.

"I'd say those were cleaning fluids, but who-"

He broke off, abruptly plucking the pendant out of John's hands, and turning it over.

"We need to find- Oh!"

He froze. Harry and John exchanged glances.

"I'll be back in a minute," he said. "I just need to… check a book. It's in my dorm."

He vanished out the door down the corridor.

"The Slytherin dorms are the other way," Potter smirked. "I knew he was lying. I imagine he's going after the kidnapper himself."

"But…"

"Don't worry, I put a tracking charm on him. He'll be leading us straight to him."

"Does he know that?"

"No. Is he always…"

"Yes."

"I'm amazed you put up with him. I've got to message my colleagues. I'll see you around."

John nodded, and when Harry left, absent-mindedly began clearing up the mess Sherlock had made. He held a blue vial up to the light. Cleaning fluids, Sherlock had said. But who in this place…

In a flash of realisation he dropped the vial, which shattered. It couldn't be.

All of a sudden he felt a warm pressure where his father's necklace hung. He pulled it out, and stroked the smooth surface. Somewhere Sherlock was in danger. Before he could figure out how he knew this, a passageway opened up in the lab wall. He knew where it led, and what he had to do.


	8. Chapter 8

**Chapter 8**

Sherlock felt guilty about lying to John, he had no intention of going to the Slytherin dorms. He checked his watch; he needed to be in the entrance hall. He was a little early, but he could wait. He leaned against the wall, pretending to examine the pendant, going over his plan. Harry Potter had acted exactly as he'd expected him to, placing that tracking charm on him. He had figured out his plan, he was sharper than he gave him credit for. As he thought, the care-taker shuffled in with his mop.

"So what really is this thing?"

Mr Carson stiffened. Sherlock turned away casually.

"It's got powerful magic, that much is obvious, but there must be something more. Why else would you be interested in collecting the set?"

He could hear the man creeping up on him.

"You're still missing-"

A hanker chief was clamped over his mouth, and he had just enough time to note the scent of chlorine before he fell unconscious.

A little while later he woke on a stone floor, the caretaker leering over him.

"Well then," he said. "Sherlock Holmes. I heard you were bright, but I didn't realise that a first year would be a danger to me."

Sherlock tried to sit up, but something in the drug had affected his limbs. That wasn't part of the plan.

"You're strong, I'm impressed. You've only been out about ten minutes."

Ten minutes. They would have found the carving by now, and his wand… he glanced around as much as was possible. He was in a dungeon of some kind, and there were two doors leading out. One probably went to outside and the other…

"Of course now you're here, the question is what to do with you. I already have an heir of Ravenclaw, I don't need you, not now that I have that pendant. Perhaps I should just-"

"Wait," croaked Sherlock. "I was wrong. You're eyes tell it all. Please listen to me, you don't know what you're doing!"

The man blinked uncertainly, so Sherlock kept going.

"You have to fight it!" he said as forcefully as he could. He gathered all his strength and worked himself upright. He forced himself to his feet, but it took effort. If he wasn't careful he would end up unconscious again.

"I know exactly what-" but then Mr Carson fell forwards with a limp thud. John was stood behind him, one arm raised. Behind _him_, the wall seemed to be sealing itself.

"John," he croaked. "But how…"

The door was blasted open, and the room flooded with Aurors.

"No!" cried Sherlock, but his little strength was draining away. "Don't hurt him," he whispered, as he fell. John caught him. "He's under the imperious curse…"

And then he fainted completely.


	9. Chapter 9

**Okay, so this is it, the final chapter. I am in the process of writing the sequel, but it may take a few weeks.**

**Chapter 9**

That night, John and Sherlock sat alone in the hospital wing. Ordinarily, Sherlock would have fought against Mrs Hudson's 'suggestion' that they stay overnight, but Mycroft had informed him that their little escapade had sped around the school like wild-fire. Neither he nor John was willing to face that just yet.

Sherlock was worried about John. He hadn't spoken much since the Aurors had found them, and had answered their questions as briefly as possible. Sherlock didn't believe half of the answers anyway, there was _no way_ that he'd followed them from the entrance hall. The Aurors had swallowed it, though. Now he was huddled in a blanket.

"Are you alright?"

"Of course I'm alright, I'm just thinking."

"Be careful, I don't want you to hurt yourself."

"Very funny. Wait, did you just make a joke?"

"What are you thinking about?"

"The imperious curse," he said softly, and Sherlock understood. "How did you know?"

"I recognised the signs."

"One of your 'experiments'?"

"Not one of _mine_, no. Lucky I was there, or we may not have been able to prove his innocence. It doesn't help us, though."

"There's no way to trace the spell caster?"

"They beat me," he fumed. "I don't like that feeling."

"They must have been close at hand," mused John. "To sustain the curse."

"Hogsmeade would have been close enough; they didn't have to be in the castle."

"Why did he take them, anyway?"

"Those pendants are elemental amulets. Apart they're powerful enough, but together I have no idea what they could do, and I don't really plan on finding out."

"But why all that stuff on the walls? He wasn't after revenge was he?"

"Unlikely, he was more interested in power. For some reason he needed the children as well, probably to work the amulets. Just making them disappear would have been good enough, but by suggesting revenge he was leading the Aurors down a false trail, you read the articles, they thought it was a death eater attack. Whoever we're dealing with, they're a genius."

"But he failed."

"Yes, he didn't find Hufflepuffs heir. You know, Hufflepuffs are often overlooked. There's more to them than meets the eye. You taught me that much."

John didn't answer, he looked troubled again.

"What else is wrong?"

"I walked right into his path, if he'd known… but I had no idea…"

"Know what?"

"I messed up, Sherlock," he said shakily. "If I hadn't been able to knock him out…"

"What are you talking about?"

John seemed to grit his teeth as he tugged at a leather strap around his neck. In a swift movement he pulled something out of his robes and handed it to Sherlock. Something yellow, but it couldn't be…

"You're the descendant of Hufflepuff?" he gasped.

"I think so," said John nervously. "But I'm a muggleborn. This was my fathers."

"A lot of muggleborns have a witch or wizard somewhere in their family tree. But this means-"

"That I was next," he sighed. "The fourth person."

"And yet you were the hardest to find. I reckon that if you needed to get away, you could have done it, and stayed hidden as long as you wanted.

"What?"

"John, Hufflepuffs element was earth. Did this thing ever open up tunnels, or secret passages?"

"A few times," he admitted.

Sherlock nodded, and then looked up sharply.

"Somebody's coming," he whispered, hanging the pendant back to John.

A few moments later, Moriarty stuck his head around the door.

"Hello!" he said brightly. "Are you both alright?"

He wandered in chirpily, sitting next to John and throwing an arm around him.

"The teachers have been filling me in," he said. "I was very impressed, the way you worked it all out."

"Thank you," said Sherlock stiffly. There was something he didn't like about the head boy.

"Why the long faces? You caught him! And it won't happen again, not on my watch."

"You leave this year."

"So I do. But don't worry, Sherlock, I'll be keeping an eye on you. You have… potential. Now your brother, he has potential as well, he wants to be head boy in a couple of years, and I expect he'll succeed, but there's just something so deliciously unorthodox about you."

"Mycroft has all the tools he needs to be intelligent, but he's too reluctant to get off his backside and do something about it."

"But you do. Do you want to be a detective, Sherlock?"

"No, I want to be a pirate."

John sniggered at this. Moriarty obviously decided that it was time to leave.

"Well, I'd best be off," he said. "Enjoy the rest of the year."

XXX

The next day, Sherlock had managed to sweet-talk Mrs Hudson into letting them go, if they promised not to attend lessons for the day. They entered the great hall at lunchtime, and John invited Sherlock to join him at the Hufflepuff table. They had planned to sneak in surreptitiously, but that didn't quite work out. As soon as Mary saw him she squealed and hugged him tightly, attracting the attention of everybody within a ten-yard radius.

"John!" cried Peter, clapping him on the back. "We heard what-"

"I don't want to talk about it," he said coolly, but people were starting to edge closer. Sherlock glared at them, scaring them away.

"I saved you this anyway," said Mary, handing a paper to Sherlock. "I wasn't sure you'd be here, actually, all the others were taken to St Mungo's. You've got a letter, John."

"Thanks, Mary. Hey, Harry got into Hogwarts!"

"I told you so," said Sherlock smugly. John rolled his eyes and turned back to Mary.

"So what else's been happening?"

"Mr Carson resigned," she said. "He just disappeared."

"Understandable," nodded Sherlock. Everyone else looked confused. John guessed that the papers hadn't named the kidnapper, and everyone seemed to be having trouble putting two and two together…

"They worked out how to remove the marks on the walls," she continued, "and Professor Williams woke up this morning to find that somebody had hung his underpants all the way down the main staircase…"

THE END

**So that's all folks! Until the next time. Please review and tell me what you think!**


	10. UPDATE

**UPDATE**

**Just thought I'd let you all know, the sequel to this story, **_**Babysitting Detail**_** is now in the process of being uploaded. Chapter 1 is up, and chapter 2 will be there shortly.**

…_The boy's strange eyes faded away as John succumbed to sleep, but the sleep was not the peaceful blackness he'd been expecting. All of a sudden he was five years old, trailing after his mother and father, who were pushing a buggy holding a sleeping Harry. They stopped at a bench to eat the biscuits they'd brought. John, however, was restless, so went to a fallen tree trunk a short distance away. He walked backwards and forwards along the top, perfectly balanced until a scuffling made him look down. He jumped away from his parents onto the ground, and found a boy huddled there. John had never seen anyone quite like him. He was scrawny, with black curls, and eyes that seemed to flick between green and grey._

"_Hello," said John._

_The boy didn't answer. He seemed scared, but his eyes appraised John coldly._

"_Lockie!" called a boy's voice in the distance. "Lockie, where are you?"_

_There was a moment's silence, then a man bellowed: "SHERLY!"_

_The boy visibly trembled, eyes wide as a hand appeared from nowhere and grabbed the boy by the collar…_


End file.
